Spy watchdog summoned to Parliament

Intelligence services watchdog Sir Mark Waller has been ordered by MPs to attend a parliamentary committee hearing after previously refusing an invitation.

In an "unusual" step, Sir Mark, the intelligence services commissioner who provides independent judicial oversight over MI6, MI5 and GCHQ, was issued a summons by the Home Affairs Select Committee at midday.

He has been ordered to attend a committee hearing on March 18, the first time the group of MPs has issued such an order.

He is likely to be grilled about the impact of disclosures made by US whistleblower Edward Snowden, who leaked top-secret documents to a number of locations, including to the Guardian newspaper, revealing details concerning America's National Security Agency and UK listening post GCHQ.

Committee chair Keith Vaz said: "The intelligence services commissioner plays a vital role in keeping under review the way in which the Home Secretary and the intelligence services use the powers which they have been granted by Parliament.

"This function was conferred on the commissioner by Act of Parliament, and Sir Mark must be accountable to Parliament for the way in which he carries them out.

"Both the information commissioner and the interception of communications commissioner have accepted invitations to give evidence to the committee in the last few weeks.

"We do not see why the intelligence services commissioner should be any different and the committee was disappointed by his refusal to attend."

He added: "We have therefore taken the unusual step of summoning Sir Mark.

"This happens only very rarely, where an essential witness declines to appear in response to an invitation. Indeed, it is the only time that this committee has summoned a witness in this parliament."

Critics have claimed Mr Snowden's disclosures have aided terrorists, while others believe the move could be illegal.

Earlier this year, MI5 director general Andrew Parker warned in a speech that revealing details about the work of GCHQ was a ''gift to terrorists'', while Sir John Sawers, head of MI6, said terrorists were ''rubbing their hands with glee''.

Supporters believe the leaks exposed an abuse of powers among the security and intelligence services in the UK and US and have contributed to a much-needed debate on their oversight and role.